1. Field of the Invention
The present invention relates to a resolver, and more specifically, to the novel improvement of a resolver for simplifying the structure thereof by eliminating a case used as a ring-shaped stator and a hollow rotating shaft used as the ring-shaped rotor as well as saving a space necessary to incorporate the resolver in a motor case.
2. Description of the Related Art
This type of prior art variable reactance resolvers are arranged as shown, for example, in FIG. 1. That is, what is denoted by numeral 1 in FIG. 1 is a ring-shaped stator having a stator winding 2 to which a lead wire 2A is connected and the outer periphery of the ring-shaped stator 1 is held by a ring-shaped case 3. A ring-shaped rotor 5 held by a hollow shaft 4 is rotatably disposed inwardly of the ring-shaped stator 1.
Since the prior art resolvers are arranged as described above, they have the following problems. That is, since the case is disposed around the outside of the ring-shaped stator, when the case is accommodated in a motor case, it is difficult to assemble the resolver inside a small motor because the outside diameter of the motor case increases as well as since the resolver uses a large number of parts, and cost reduction thereof is difficult.
Further, since the hollow shaft is disposed inwardly of the ring-shaped rotor, the outside diameter of the resolver is increased by the wall thickness of the hollow shaft and cost reduction is made difficult by the number of parts used.
An object of the present invention is to provide a resolver whose structure is simplified by eliminating a case used as a ring-shaped stator and a hollow rotating shaft used as a ring-shaped rotor as well as saving the space necessary to incorporate the resolver in a motor case.
A resolver according to the present invention comprises a ring-shaped rotor that is composed of a magnetic material, does not include a winding and is rotatably disposed inwardly of a ring-shaped stator having a stator winding, wherein the outer periphery of the ring-shaped stator is directly exposed and as the inner periphery of the ring-shaped rotor is directly exposed.
More specifically, the outer periphery of the ring-shaped stator is in direct contact with the inner periphery of a motor case and the inner periphery of the ring-shaped rotor is in direct contact with the outer periphery of the motor rotating shaft in the motor case.